Illinois State Police Trooper Doug Francis said he had no reports of fatalities or number of injuries about two hours after the crash of the discount charter bus, which the company said was traveling from Chicago to Kansas City. He said 30 ambulances and 10 medical helicopters were sent to the scene.

“We received a report it had blown a tire which caused it to run off the road,” Francis said. “The bus did stay upright.”

Television helicopter footage shows numerous emergency vehicles surrounding the bus and rescue crews climbing ladders to reach inside its crumpled front end. Some passengers could be seen being tended to along the side of Interstate 55, which was shut down in both directions.

MegaBus spokeswoman Amanda Byers said the bus was at full capacity, carrying 81 passengers, when it crashed near Litchfield, about 55 miles northeast of St. Louis. The bus also was to stop in St. Louis and Columbia, Mo.